This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A257352 #17 Sep 01 2025 15:52:03
%S A257352 1,1,51,151,301,501,751,1051,1401,1801,2251,2751,3301,3901,4551,5251,
%T A257352 6001,6801,7651,8551,9501,10501,11551,12651,13801,15001,16251,17551,
%U A257352 18901,20301,21751,23251,24801,26401,28051,29751,31501,33301
%N A257352 G.f.: (1-2*x+51*x^2)/(1-x)^3.
%C A257352 An example of a quadratic sequence for which the continued square root map (see A257574) produces the number 2. There are infinitely many sequences with this property - another example is A028387.
%H A257352 Harvey P. Dale, <a href="/A257352/b257352.txt">Table of n, a(n) for n = 0..1000</a>
%H A257352 Popular Computing (Calabasas, CA), <a href="/A257352/a257352.pdf">The CSR Function</a>, Vol. 4 (No. 34, Jan 1976), pages PC34-10 to PC34-11. Annotated and scanned copy.
%H A257352 Herman P. Robinson, <a href="/A257574/a257574.pdf">The CSR Function</a>, Popular Computing (Calabasas, CA), Vol. 4 (No. 35, Feb 1976), pages PC35-3 to PC35-4. Annotated and scanned copy.
%H A257352 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%t A257352 CoefficientList[Series[(1-2x+51x^2)/(1-x)^3,{x,0,40}],x] (* or *) LinearRecurrence[{3,-3,1},{1,1,51},40] (* _Harvey P. Dale_, Sep 01 2025 *)
%o A257352 (PARI) a(n)=25*n^2-25*n+1 \\ _Charles R Greathouse IV_, Jun 17 2017
%Y A257352 Cf. A257574. A028387.
%K A257352 nonn,easy,changed
%O A257352 0,3
%A A257352 _N. J. A. Sloane_, May 03 2015